CORRELATION OF THE MIDDLE TRIASSIC DEPOSITS IN THE NORTH CASPIAN AND GERMANIC BASINS

Abstract

The analyzed distribution ranges of tetrapods, ostracods, megaspores, and other fossils were used, with due regard for the facial dependence and phylomorphogenetic lineage, to resolve correlation problems concerning Triassic sections of the Germanic and North Caspian basins and southern Cis-Urals, and also to correlate them with the general stratigraphic scale of the Triassic. The Inder and Donguz formations of the North Caspian basin and Cis-Urals are proved to be early-middle Anisian in age. They correspond to the upper Rt (upper Buntsandstein) and lower Muschelkalk (lower-middle Wellenkalk) of the Germanic basin. The Sarpa and Masteksai formations of the North Caspian basin, along with the Yushatyr and Bukobai formations and a lower part of the Surakai Formation, are dated back to the late Anisian-Ladinian and correlated with the upper-most middle-upper Muschelkalk (its Anhydrite Group and Hauptmuschelkalk) and Lettenkeuper of the Germanic basin. A hiatus separating the Inder Formation from the Sarpa Formation and the Kiil Formation from the Masteksai Formation in the North Caspian region is coeval with that separating the Donguz and Yushatyr formations of the southern Cis-Urals. It appears to be a consequence of regression also recorded in the middle Muschelkalk (middle Illyrian) of Germany. In the North Caspian basin and Cis-Urals, the hiatus ranges from the middle-terminal Pelsonian to the mid-Illyrian.